1. Field of Invention
The present invention relates to a medical device, and more particularly to a device which is adapted for infusing a liquid into the vessel of human body.
2. Description of Related Arts
Intravenous infusion (currently called infusion) remains the major procedure for clinical care and treatment, particularly, in the intensive care unit, emergency room, etc., immediately establishing the intravenous transfusion is often the key elements of life-saving.
Rapidly establishing the intravenous transfusion depends on both a health care professional's first-stick success technique, and the patient's vein thickness and its position.
The traditional intravenous infusion technique is using a rigid (metal) needle to penetrate the vessel for infusing liquid medicine. After infusion, the needle has to be pulled out. In most cases, repeated infusion procedure is needed for treatment. Therefore, patients have to suffer from needle stick for each infusion.
In patients with chronic diseases, longtime infusion is often needed. In these patients, steel needle has to be remained in the patients' vessel for a long time. Sometime the steel needle tip penetrates the vessel wall while the limb is moved. This failure of the infusion can cause bleeding and fluid extra-vasation that can cause pain and surrounding tissue edema and damage. Thus, the needle must be pulled out and another vessel penetration is not avoidable.
Current technology has used the soft plastic catheter for intravenous infusion (Chinese Patent CN2163653Y, 05/041994). After a soft plastic catheter as a sleeve on the steel needle be used for penetrating the vessel wall, the steel needle will be pulled out, then the catheter will be remained in the vessel for infusion. The catheter will then be connected to the intravenous infusion set. Thus, the soft plastic catheter will not injured and penetrate the vessel wall during infusion as that seen in needle set, the repeated needle stick is avoid.
However, all of infusion catheters have the blunt-cutting edge on its tip. The flat edge is 90° to the long axis catheter wall (as shown in FIG. 3 of Chinese patent CN1468637A). The catheter tip is relatively soft and blunt. It is not so easy to be inserted into the vessel wall as the steel needle tip, since there is a certain resistance when it penetrating through the vessel wall. Sometimes, the edge of the tip will be dilated as “bell” shape, or tear, due to the extra force is used for insertion, the catheter can not be inserted into the vessel, then the catheter must be changed and reinserted.
Additionally, the design of the handle of the catheter-needle currently available is round shape, it is not easy to be fixed on the body surface. This is another disadvantage of the current design.
On another hand, recent advance in the design of infusion catheter has been focused on effectively safeguard healthcare workers from accidental needle stick injuries. In a Chinese patent CN1135122C, published in Jan. 21, 2004 has shown the design of a “multipurpose safety intravenous infusion catheter needle” that consist with a trifurcate connector, an infusion soft needle, a steel needle, and an infusion catheter. The first and second connector on the trifurcate connector is the one the same axial and toward to the needle tip. There is a rubber cap on the end of the second connector. The soft needle catheter is on the first connector. The steel needle body slidably fitted in a sleeve and axially passed in the soft needle. The sleeve is connected with the second connecting section of the trifurcate connector. An infusion catheter is connected with a third connecting section of the trifurcate connector. After the soft needle catheter inserted into the patient's vein with the steel needle, the steel needle will be pulled out from the end of the sleeve, the needle will be kept in the sleeve, this improvement can avoid the needle exposed, which can caused accidental needle-stick injury to the others, then cause infection.
However, this design still has some short-comings:                1) The steel needle has to be pulled out from the soft needle catheter manually, this distance is not so short, so it is not so convenient for the operator;        2) The trifurcate is not so easy to handle. More particularly to patients with obesity, excessive bleeding, dehydrate, etc., the vein is hard to find, it is difficult to find the vein and insert the needle catheter quickly and accurately for the healthcare professional. Thus, it is not only waist the time, and also can cause the unnecessary suffering for the patients.        3) The outside contours of the cross section profile of the trifurcate soft needle catheter is round shaped, it is difficult to be fixed on the patients' body surface, it is also easy to be rotated or moved after it be fixed during the infusion.        